What’s a Turing machine? It’s not an actual machine, per se, but a thought experiment that allowed for the advent of digital computing.
…an
unlimited memory capacity obtained in the form of an infinite tape
marked out into squares, on each of which a symbol could be printed. At
any moment there is one symbol in the machine; it is called the scanned
symbol. The machine can alter the scanned symbol and its behavior is in
part determined by that symbol, but the symbols on the tape elsewhere do
not affect the behaviour of the machine. However, the tape can be moved
back and forth through the machine, this being one of the elementary
operations of the machine. Any symbol on the tape may therefore
eventually have an innings.
Turing went on to head the team at Bletchley Park that decoded
Germany’s Enigma encryption machine, thereby turning the tide of the
war. The British government subsequently sentenced him for “gross
indecency” – homosexuality – and offered him prison or chemical
castration. He chose the latter and killed himself two years later.